Beverage preparation devices for preparing instant beverage or for preparing coffee from an extract or from ground beans are known where ground coffee or water soluble powder or a beverage concentrate is brought into contact with hot or cold water in a preparation unit. The brewing unit can for instance include a filter ground coffee preparation unit through which hot water is supplied. It is also possible for the brewing unit to include a container that compresses the charge of ground coffee into a coffee bed through which hot water, pressurised for example by between 1-10 bar, is forced through to prepare espresso coffee. The preparation unit can also receive instant powder for preparing a beverage and a mixing device for dissolving the powder in a volume of water supplied to the preparation unit.
The user instructs the control unit via a control unit, which may include multiple buttons, as to which type of drink and the quantity that should be dispensed by the preparation unit to a container, such as a cup or jug. If larger quantities of beverage are required to be dispensed, the user can leave the container under the outlet of the preparation unit for several consecutive preparation cycles. The downside is that the moment when the final amount of beverage is dispensed, is unclear for the user and that there is a pause between consecutive preparation cycles that gives the impression that the beverage delivery has ended. Early removal of the container by the user can, if the next preparation cycle commences, give rise to spills and beverage release outside the container.
An alternative to preparing larger quantities of drink is the use of a preparation unit with a larger content. This allows the volume of the beverage dispensing device to increase to unwanted dimensions and to become too large for certain applications. The technique is also known where electrically controlled valves are installed in the hot water and cold water supply lines of the preparation unit, as well as in the drain in order to prepare different volumes of beverage in the preparation unit. However, these valves are prone to malfunctions and are maintenance intensive.
A beverage preparation device according to the introduction of claim 1 is known from WO98/27852. This publication described a dispensing device for a post-mix multiple station in which the prepared beverage is stored in a storage tank. When beverage is drawn from the storage tank beverage, the level of the liquid is measured by sensors and when a predefined set level is reached, new beverage is supplied to the storage tank.
The known device has the disadvantage that the time the drink remains in the storage tank can be relatively long, whereby the quality of the beverage is adversely affected. The taste of coffee is very susceptible to the storage time and the known device is unsuitable for issuing of fresh coffee. The temperature of cold or hot beverages can also fluctuate unacceptably due to the time spent in the storage tank.
In view of the above, the intention of the invention is to provide a device for preparing beverages in with which both small and larger amounts of beverage can be dispensed to a user in a fool proof way, without adversely affecting the quality of the beverage. It is a further intention of the invention to provide a device in which the preparation unit has a relatively compact size and where the use of malfunction-prone valves is avoided.